Various elongated parts such as but not limited to wires, mandrels, needles, and probes are widely known. During the manufacturing processes for such elongated parts, the outer circumferential dimensions (that are often 0.005 inches (0.127 mm) or smaller) of such parts often need to be measured during various stages of the manufacturing process.
In one example, wires (such as guide wires configured to enter the human body for various different types of medical procedures) often need to be measured during manufacturing processes as described below. Guide wires used in certain medical procedures are used as an example herein to explain certain problems with the measuring of various, elongated parts such as elongated parts having a fine or small outer diameter such as from 0.002 inches (0.0508 mm) to 0.038 (0.9652 mm) inches for different elongated parts or on the same elongated part, and are very flexible by design.
In another example, mandrels also often need to be measured during manufacturing processes. Various mandrels have a small outer diameter such as much as 0.0375 inches (0.9525 mm) (or even smaller outside diameters) and larger diameters up to about 0.500 inches (1.27 mm).
The lengths of guide wires used for medical procedures typically vary from about 4 feet (about 1.2 meters) to about 14 feet (about 4.2 meters), and can be even shorter or longer. Various types of guide wires are formed from solid cylindrical metal wires, often with multiple outer dimensions and tapers at a distal end. Various other types of guide wires are formed from metal coils that comprise very fine wire (e.g., such as having a 0.007 inch (0.1778 mm) outer diameter) is formed into the metal coils with outer diameters in the range of 0.012 inches (0.3048 mm) to 0.038 inches (0.9652 mm). These metal guide wires provide extreme flexibility while still providing sufficient rigidity. These metal guide wires are primarily made from stainless steel (but can also be made from nitinol or other alloys). Such metal guide wires typically need to be coated with a suitable coating to provide the guide wire with a bonded smooth outer polymer surface such as PTFE or an ablative hydrophilic surface to prevent injury to the intravascular system of the person in which the guide wire is inserted and to provide consistent tactile feedback to the surgeon or medical professional. For purposes of this disclosure, wires and guide wires are meant to include, but not be limited to, (1) single individual wires with a single or multiple outer diameter dimensions; (2) very fine wires that are formed into a coil that can have a single outer diameter dimension or multiple outer diameter dimensions (as well as solid wires often called mandrels); and/or (3) coiled guidewires that have rigid or semi-rigid metal, polymer, or “floppy tips” attached to the distal end of the guide wire (which can be comprised of different alloys, and/or polymer tips or combinations thereof).
Example known individual guide wires are coated with low friction, relatively inert coatings that include polytetrafluoroethylene (“PTFE”) such as Chemours TEFLON® coating or Whitford XylaMed® coatings. Other example guide wire coatings include combinations of other fluoropolymers, such as fluorinated ethylene propylene (“FEP”) and perfluoroalkoxy (“PFA”), which enhance certain characteristics of the finished coating and impart functional characteristics such as low friction, non-stick, and electrical and chemical resistance. Other example elongated parts are made of stainless steel (such as metal mandrels) and have a generally consistent outer diameter and are commonly coated with PTFE, FEP or PFA for nonstick purposes prior to being used to form an inside diameter of a flexible polymer tube through an extrusion process. Additional known coatings include hydrophilic coatings. All of these coatings are bonded to the original outer surface of the elongated part and add to the diametric outer dimension of the uncoated elongated part (such as the uncoated coiled or single dimension formed elongated wire).
Uncoated guide wires are typically manufactured by one company (i.e., a manufacturer) and sent to another company (i.e., a coater) that specializes in applying coatings to products such uncoated guide wires. Guide wire manufacturers require that the coating is applied to the uncoated guide wire within specific upper and lower dimensional tolerances or tolerance levels including specific outer diameters. Guide wire manufacturers also typically have minimum and maximum amounts of the coating that may be applied to any section of the guide wire. Guide wire manufacturers also sometimes require that portions of the guide wires be masked to provide the guide wires with distance markings from the proximal or distal end of the guide wire.
To meet these specific manufacturer requirements, a coater will often need to measure the outer diameter of the received uncoated guide wire before applying the coating. This can be done for each received uncoated guide wire of a batch of uncoated guide wires, or for a designated sample or quantity of the batch of uncoated guide wires. In other words, even before the coating is applied, the uncoated guide wires are often measured to establish and verify the actual outer diameters of the guide wires to be coated. A cleaning process is typically used prior to the measuring of the raw, uncoated wire. In certain instances, if an uncoated guide wire has one or more outer dimensions (along its length) below or above the particular outer dimension tolerances, the uncoated guide wire is not coated and is sent back to the guide wire manufacturer as not within specifications. In other instances, if an uncoated guide wire has too large of an outer diameter (along it length), the coater alerts the guide wire manufacturer of this fact and a decision is made whether to return the guide wire, to scrap the guide wire, or to apply a thinner coating (than specified to the guide wire provided that it meets the lower limit of the coating thickness, and so that the overall outer diameter (along the length) of that guide wire including the coating are under a certain upper limit for the outer diameter. For certain coating systems, the measurements of an uncoated guide wire are used to determine the amount of coating needed to apply to the uncoated guide wire to bring it within the required outer diameter tolerances of the guide wire and the coating to be applied, provided that the applied coating can be applied within the diametrical requirements of the coated wire. Many coatings must be applied to a maximum thickness which would preclude some of the additive coating to add to the dimension from increasing the diameter sufficiently.
Additionally, to meet the specific manufacturer requirements, a coater will also typically need to measure the outer diameters of the coated guide wires after applying the coating. This can be done for each coated guide wire of a batch of coated guide wires, or for a designated sample or quantity of the batch of coated guide wires. In other words, after the coating is applied, the coated guide wires are measured to ensure that the coated guide wires do not have any outer dimensions (along their length) below or above the particular outer dimension tolerances. In other words, the outer dimensions must not be below or above the particular outer dimension tolerances after being coated. If a coated guide wire is below or above the allowed outer dimension tolerance range, the coated guide wire is considered non-conforming and typically cannot be corrected (by adding to or reducing the coating thickness), and cannot be used for its intended purpose. More specifically, if the coated guide wire has too large of an outer diameter (along any portion of its length), the outer dimension often cannot be reduced to meet the desired specifications. Similarly, if the coated guide wire is too small after applying the coating, additional coating typically cannot be applied because the original coating has cured and additional layers of final cured PTFE coating cannot be applied because the coating, and particularly if the coating is PTFE, cannot generally have a second coat applied to a final cured PTFE first coating. Specifically, this is the case because the bond strength between the cured first layer and a second layer would be insufficient for a medical device (such as a guide wire) entering the human vascular system and could result in potential delamination between the surface of the first coat and the second outer coat.
This is also true for mandrels that are used in an industrial environment where a peeled or dislodged portion of coating would render the mandrel useless, and where the part that was formed over the mandrel would then have a contaminant inside it.
Additionally, certain guide wire manufacturers require a top coat to be placed over the primary coating layer which can be done with certain primary coatings, certain top coatings, and for certain coating processes. Thus, in some instances, the outer diameters of the guide wires need to be measured after the primary coating is applied and before the top coating is applied.
Additionally, to meet various manufacturer requirements, a coater may need to take into consideration that an uncoated guide wire may have different outer dimensions along its length. For example, an uncoated guide wire may be tapered from one end to the other end, generally referred to as the proximal and distal ends. A tapered guide wire typically has a smaller dimensional end that functions as a softer end (that is easier to manipulate or steer) for movement through the vascular or urinary system. For example, a guide wire may be reduced from 0.012 inches (0.3048 mm) to 0.004 inches (0.1016 mm) for about 12 inches (304.8 mm) at one end of the guide wire. These tapered guide wires need to be measured and have the taper verified. Thus, a coater will typically need to measure the outer diameter of the uncoated and the coated tapered guide wire at multiple spaced apart sections along the guide wire before and after applying the coating, respectively. Since the guide wires can be up to about 14 feet (about 4.2 meters) long, this includes taking numerous measurements of the sections of the guide wire along its length (such a measurement every 2 feet (about 0.61 meters) along the length of the guide wire).
In further instances, a guide wire manufacturer may require that one or more portions of the guide wire have no coating, exposing the uncoated stainless steel or metallic or polymer jacketed surface. These uncoated areas are typically used for distance referencing during a medical procedure. In certain such instances, the outer dimensions of the uncoated portions must be verified and documented. Because these uncoated areas are smaller than the coated areas, there is often a need to measure the location, with and/or placement of these uncoated areas.
Currently, the known process for measuring uncoated and coated elongated parts is time consuming and labor intensive and requires moving the elongated part (such as the guide wire or mandrel) through a measuring device. For example, this known process includes a worker manually moving the guide wire (whether before or after coating) to a measuring station, and then taking each of the measurements at each desired point along the length of the guide wire. This specifically includes the worker positioning the guide wire at a first desired point along the length of the guide wire and taking the measurement, and then moving the guide wire to repeat this process for each desired point of measurement along the length of the guide wire. For each such measurement along the length of the guide wire, the portion of the guide wire to be measured is positioned at a measuring station for that measurement. These multiple contacts of and physical manipulations of a coated guide wire can damage the coating or polymer sheath or covering on the guide wire (such as causing abrasions to or crushing or scratching of the coating on the guide wire). This is especially prevalent when the guide wire needs to be centered in a pair of Vee blocks, in an area for measurement. The various movements of and handling of the elongated part (such as a guide wire or mandrel) thus subjects the elongated part (such as the guide wire or mandrel) to potential damage. For a 14 foot (about 4.2 meters) long guide wire, this can include six or more separate measurements and six or more separate significant movements of the guide wire. It should be appreciated that certain fluoropolymer coatings such as PTFE, FEP and PFA or a hydrolytic coating that are applied to the outer diameter of a guide wire are relatively soft and compressible, and that such additional handling can damage such coatings.
In other examples, coating systems that use a handheld measuring device to obtain such measurements often result in inaccurate measurements because the jaws or anvils of the handheld measuring devices can deform or crush the coating on the guide wire as these devices must actually touch the surface of the wire/coating to provide a physical measurement.
In another known measuring method, a guide wire (or mandrel) is gripped at both ends and stretched tight on a reciprocating device that moves the guide wire in the measuring area of a laser micrometer. This requires actual physical gripping and holding, very tightly, of the guide wire, which particularly at the distal end, can be very, very delicate. In addition, as mentioned above, a guide wire formed from a coiled spring can be stretched and deformed by gripping it (i.e., by gripping both the distal and proximal ends and applying a force to straighten the guidewire between these two grip points). This stretching can cause inaccurate measurements of the outer dimensions.
It should also be appreciated that there are certain difficulties in holding these elongated flexible parts by the ends of the elongated parts.
In addition to guide wires that are configured to enter the human body, there are many other elongated parts that don't enter the human body such as mandrels (or forming mandrels). Certain of these mandrels form the inside of a rubber tube (such as a PEBAX rubber tuber or another flexible polymer tube). The rubber or polymer is typically extruded over the mandrel. The mandrel provides the rubber tube (or flexible polymer) with a precise inner diameter. These mandrels can be as long as 20 feet (about 6.10 meters) but are typically in the range of 6 to 10 feet (about 1.88 to 3.05 meters) long. These mandrels must be measured before use (i.e., before being coated with the rubber coating). Additionally, the outer diameters (along the length) of the elongated rubber tubes must also often be measured for compliance with manufacturer specifications.
Additionally, many finished guide wires are comprised of a flat or round coiled spring configuration with a welded nitinol tip and/or a jacketed nitinol or stainless steel tip attached to the coiled spring. These hybrid type guide wires, especially those coated with a hydrophilic coating at the distal end and a PTFE coating on the majority of the guide wire, can be subjected to excess handling that removes the hydrophilic coating (i.e., through digital handling and manipulation during the known measurement processes). Holding devices (such as Vee blocks) can actually remove or scrape the coating if the operator doesn't lift and replace the guide wire onto the holding devices (such as into the Vee blocks) rather than drag the guide wire through the holding device (such as the Vee blocks).
Accordingly, there is a need for a measuring apparatus and method that can be used to quickly and accurately measure multiple outer diameters of an elongated part (such as a wire or mandrel) at multiple points along the length of the uncoated or coated elongated part—without the significant amounts of manual movements (and labor) currently needed, without holding or stretching the elongated part between two points, without dragging the elongated part through holding devices (such as a pair of Vee blocks or alignment blocks), without applying undesired forces to the elongated part, and for enabling certain elongated parts (such as hybrid guide wires or any other guide wires) to “relax” while being measured, all in a significantly shorter time frame, and with accuracy measured in microns and without potential distortion, disruption, or abuse to the coating that is attached to the outer surface of the uncoated elongated part. Additionally, there is a need for a measuring apparatus that will measure the entirety of (including the absolute proximal and distal ends of) the elongated part (such as a guide wire or mandrel) without the need to hold the elongated part.